Online PHP editor | output for JCJ6p

<?php $a = [ [ 'FIRSTID' => 58, 'SECONDID' => 12, 'TYPE' => 319, 'AMOUNT' => 300 ], [ 'FIRSTID' => 58, 'SECONDID' => 12, 'TYPE' => 319, 'AMOUNT' => 600 ], [ 'FIRSTID' => 59, 'SECONDID' => 14, 'TYPE' => 321, 'AMOUNT' => 900 ], [ 'FIRSTID' => 59, 'SECONDID' => 14, 'TYPE' => 321, 'AMOUNT' => 500 ], [ 'FIRSTID' => 60, 'SECONDID' => 13, 'TYPE' => 320, 'AMOUNT' => 1000 ], [ 'FIRSTID' => 60, 'SECONDID' => 13, 'TYPE' => 321, 'AMOUNT' => 1500 ] ]; $r = []; foreach($a as $v){ array_key_exists($v['FIRSTID'], $r) ? ($r[$v['FIRSTID']]['AMOUNT'] += $v['AMOUNT']) : $r[$v['FIRSTID']] = $v; } echo '<pre>'; print_r($r);